Genetic Control and Evolution of Sesquiterpene Biosynthesis in Lycopersicon esculentum and L. hirsutum

Abstract

Segregation analysis between Lysopersicon esculentum (cultivated tomato) and L. hirsutum (wild form) in conjunction with positional verification by using near-isogenic lines demonstrated that biosynthesis of two structurally different classes of sesquiterpenes in these species is controlled by loci on two different chromosomes. A locus on chromosome 6, Sesquiterpene synthase1 ( Sst1 ), was identified for which the L. esculentum allele is associated with the biosynthesis of ␤ -caryophyllene and ␣ -humulene. At this same locus, the L. hirsutum allele is associated with biosynthesis of germacrene B, germacrene D, and an unidentified sesquiterpene. Genomic mapping, cDNA isolation, and heterologous expression of putative sesquiterpene synthases from both L. esculentum and L. hirsutum revealed that Sst1 is composed of two gene clusters 24 centimorgans apart, Sst1-A and Sst1-B , and that only the genes in the Sst1-A cluster are responsible for accumulation of chromosome 6-associated sesquiterpenes. At a second locus, Sst2 , on chromosome 8, the L. hirsutum allele specified accumulation of ␣ -santalene, ␣ -bergamotene, and ␤ -bergamotene. Surprisingly, the L. esculentum allele for Sst2 is not associated with the expression of any sesquiterpenes, which suggests that cultivated tomato may have a nonfunctional allele. Sesquiterpene synthase cDNA clones on chromosome 6 do not cross-hybridize on genomic DNA gel blots with putative sesquiterpene synthases on chromosome 8, an indication that the genes in Sst1 and Sst2 are highly diverged, each being responsible for the biosynthesis of structurally different sets of sesquiterpenes.

Monoterpenes in the glandular trichomes of tomato are synthesized from a neryl diphosphate precursor rather than geranyl diphosphate

“…Based on previous work, ␦-elemene is probably a decay product of germacrene C produced under elevated temperature of the GC inlet (23). Previous reports indicated that two sesquiterpene synthases genes on chromosome 6, designated SSTLE1 and SSTLE2, are responsible for the synthesis of sesquiterpenes in type VI glands (20,21).…”

“…Previous reports indicated that trichomes on the surface of tomato leaves, stems, and green fruit produce monoterpenes and sesquiterpenes (16,(19)(20)(21). We analyzed terpene content by using gas chromatography-mass spectrometry (GC-MS) in leaf trichomes by briefly dipping detached leaflets in tert-butyl methyl ether (MTBE).…”

“…Two other contigs with a total of 719 sequences (0.29% of total reads) were identical with the tomato sesquiterpene synthase SSTLE1/2 (GenBank accession no. AF279453) from chromosome 6 (20). Finally, a second abundant transcript (741 reads; 0.30%) represented a gene that we designated as PHS1 (for phellandrene synthase 1) (see below) (Fig.…”

The Variability of Sesquiterpenes Emitted from Two Zea mays Cultivars Is Controlled by Allelic Variation of Two Terpene Synthase Genes Encoding Stereoselective Multiple Product Enzymes

“…Genes encoding terpene synthases might actually be expected to have more rapid rates of sequence divergence than other genes if secondary metabolism is under selection for increasing diversity. In this regard, gene duplication can be seen as an evolutionary process that can make an important contribution to generating diversity in terpene biosynthesis (Facchini and Chappell, 1992;Van der Hoeven et al, 2000;Aubourg et al, 2002). Many other genes of secondary metabolism also appear to have arisen from tandem duplication events (e.g., Pichersky and Gang, 2000;Kliebenstein et al, 2001;Kroymann et al, 2001;Reintanz et al, 2001;Clauss and Mitchell-Olds, 2003).…”

Tomato leafminer [(Tuta absoluta Meyrick) (Lepidoptera: Gelechiidae)] and its current ecofriendly management strategies: A review

“…Furthermore, a number of sesquiterpenes such as δ-elemene have been found to increase in the headspace of tomato plants with T. absoluta eggs (Anstasaki et al, 2015). However, these compounds are reported to play a role in tomato resistance against insects other than T. absoluta (Van der Hoeven et al, 2000;Bleeker et al, 2009). The production of such compound is aggravated when the environmental conditions are changed.…”